Prostate-specific membrane antigen-positron emission tomography (PSMA-PET) of prostate cancer: current and emerging applications

Prostate-specific membrane antigen-positron emission tomography (PSMA-PET) is transforming the management of patients with prostate cancer. In appropriately selected patients, PSMA-PET offers superior sensitivity and specificity compared to conventional imaging (e.g., computed tomography and bone scintigraphy) as well as choline and fluciclovine PET, with the added benefit of consolidating bone and soft tissue evaluation into a single study. Despite being a newly available imaging tool, PSMA-PET has established indications, interpretation guidelines, and reporting criteria, which will be reviewed. The prostate cancer care team, from imaging specialists to those delivering treatment, should have knowledge of physiologic PSMA radiotracer uptake, patterns of disease spread, and the strengths and limitations of PSMA-PET. In this review, current and emerging applications of PSMA-PET, including appropriateness use criteria as well as image interpretation and pitfalls, will be provided with an emphasis on clinical implications.

Addressing gaps in healthcare provider knowledge regarding germline testing for prostate cancer through development and testing of a virtual genetics board

BACKGROUND

Germline testing is important in prostate cancer and evaluation can be complex.

METHODS

We instituted a monthly multi-disciplinary virtual genetics tumor board (7/2021-3/2022). Participants and panelists were surveyed on usefulness and acceptability.

RESULTS

101 participants attended a session, and 77 follow-up surveys were completed. Over 90% participants and 100% panelists endorsed usefulness of the case discussions and usability of the technology. The majority felt it provided new information they will use.

CONCLUSIONS

A multidisciplinary genetics board was successfully developed to address complexity in prostate cancer genetics. The virtual platform may enhance dissemination of expertise where there are regional gaps.

Prostate and metastasis-directed focal therapy in prostate cancer: hype or hope?

INTRODUCTION

The paradigm of focal therapy's role in metastatic patients is being challenged by evolving attitudes and emerging data. At the current time, specifically regarding prostate cancer, does the evidence indicate this is more hype or hope?

AREAS COVERED

We searched the literature via PubMed, MEDLINE, and Embase for studies from 2014 to the present addressing focal therapy with non-palliative intent in metastatic prostate cancer patients, emphasizing prospective trials when available. We sought to address all common clinical scenarios: de novo synchronous diagnosis, oligorecurrence, oligoprogression, and mCRPC disease.

EXPERT OPINION

Current evidence is strongest, and in our opinion practice-changing, for prostate-directed RT in de novo metastatic patients with low metastatic burden. Metastasis-directed therapy with SBRT is consistently shown to have low rates of toxicity, and promising rates of ADT-free survival and progression-free survival. These can be utilized on a patient-by-patient basis with these endpoints in mind, but do not yet show sufficient benefit to be standard of care. This is a rich area of ongoing research, and many trials should publish in the coming years to shed light on many unanswered questions, including the role of cytoreductive prostatectomy, systemic therapy combined with MDT, and the integration of modern PET imaging.

Radiomic Analysis to Predict Histopathologically Confirmed Pseudoprogression in Glioblastoma Patients

Purpose

Pseudoprogression mimicking recurrent glioblastoma remains a diagnostic challenge that may adversely confound or delay appropriate treatment or clinical trial enrollment. We sought to build a radiomic classifier to predict pseudoprogression in patients with primary isocitrate dehydrogenase wild type glioblastoma.

Methods and Materials

We retrospectively examined a training cohort of 74 patients with isocitrate dehydrogenase wild type glioblastomas with brain magnetic resonance imaging including dynamic contrast enhanced T1 perfusion before resection of an enhancing lesion indeterminate for recurrent tumor or pseudoprogression. A recursive feature elimination random forest classifier was built using nested cross-validation without and with O⁶-methylguanine-DNA methyltransferase status to predict pseudoprogression.

Results

A classifier constructed with cross-validation on the training cohort achieved an area under the receiver operating curve of 81% for predicting pseudoprogression. This was further improved to 89% with the addition of O⁶-methylguanine-DNA methyltransferase status into the classifier.

Conclusions

Our results suggest that radiomic analysis of contrast T1-weighted images and magnetic resonance imaging perfusion images can assist the prompt diagnosis of pseudoprogression. Validation on external and independent data sets is necessary to verify these advanced analyses, which can be performed on routinely acquired clinical images and may help inform clinical treatment decisions.

Pan-cancer Analysis of CDK12 Alterations Identifies a Subset of Prostate Cancers with Distinct Genomic and Clinical Characteristics

BACKGROUND

CDK12 genomic alterations occur in several tumor types, but little is known about their oncogenic role and clinical significance.

OBJECTIVE

To describe the landscape of CDK12 alterations across solid cancers and the clinical features of CDK12-altered prostate cancer.

DESIGN, SETTING, AND PARTICIPANTS

A single-center retrospective study of 26743 patients across 25 solid tumor types who underwent tumor sequencing was performed. Clinicopathologic features and outcomes were assessed in prostate cancer.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

CDK12 alterations and their association with genomic characteristics are described. For prostate cancer patients, overall survival and time to castration resistance were assessed using univariable and multivariable Cox regression analysis.

RESULTS AND LIMITATIONS

CDK12 alterations were identified in 404/26743 patients (1.5%) overall, but were most frequent in prostate (100/1875, 5.3%) and ovarian cancer (43/1034, 4.2%), in which they were associated with a high prevalence of truncating variants and biallelic inactivation. CDK12 alterations defined a genomic subtype of prostate cancer with a unique copy-number alteration profile and involvement of distinct oncogenic pathway alterations, including cell-cycle pathway genes. CDK12-altered prostate cancer was associated with somewhat more aggressive clinical features and shorter overall survival (median 64.4 vs 74.9 mo; p=0.032) independent of standard clinical factors and tumor copy-number alteration burden (adjusted hazard ratio 1.80, 95% confidence interval 1.12-2.89; p=0.024). The study is limited by its retrospective nature.

CONCLUSIONS

CDK12 alteration is a rare event across solid cancers but defines a clinically distinct molecular subtype of prostate cancer associated with unique genomic alterations and slightly more aggressive clinical features.

PATIENT SUMMARY

CDK12 gene alterations occur rarely across tumor types, but more frequently in prostate cancer, where they are associated with genomic instability, cell-cycle pathway gene alterations, and somewhat worse clinical outcomes, warranting further investigation of therapeutic targeting of this disease subset.

Abstract 1308: CDK12 alterations define a distinct molecular subtype of prostate cancers with unique genomic and clinical characteristics

Background: CDK12 alterations are present in several tumor types but little is known regarding their oncogenic role and their clinical significance. Here we sought to describe the landscape of CDK12 alterations across solid cancers and the clinical features of CDK12-altered prostate cancer.

Methods: A total of 26,743 patients across 25 solid tumor types with available targeted sequencing data from MSK-IMPACT as part of their clinical care were included. Clinicopathological features and outcomes were assessed in prostate cancer. CDK12 alterations and association with genomic characteristics are described. For prostate cancer patients, overall survival from the date of metastasis and time to castration-resistance from the start of androgen deprivation therapy were assessed using univariable and multivariable Cox regression analysis.

Results: CDK12 alterations were identified in 404/26,743 (1.5%) patients overall, but were most frequent in prostate (100/1875, 5.3%) and ovarian cancer (43/1034, 4.2%) where they were associated with a high prevalence of truncating variants and biallelic inactivation. CDK12 alterations defined a distinct subtype of prostate cancer with more aggressive clinical features, a unique copy number alteration profile and involvement of distinct oncogenic pathway alterations, including cell cycle pathway genes. Independent of standard clinical factors and genomic instability, CDK12-altered prostate cancer patients were associated with shorter overall survival (median 64.4 vs 74.9 months, adjusted hazard ratio [aHR] 1.65, 95% CI 1.07-2.53, p = 0.03) and shorter time to the development of castration-resistant disease (median 10.8 months vs 13.1, aHR 1.43, 95%CI 1.07-1.8, p = 0.02).

Conclusions: CDK12 loss of function is a rare event across solid cancers but defines a distinct molecular subtype of prostate cancer that is associated with more aggressive clinical features and unique genomic alterations.

Citation Format: Bastien Nguyen, Jose Mauricio Mota, Subhiksha Nandakumar, Konrad H. Stopsack, Emily Weg, Dana Rathkopf, Michael J. Morris, Howard Scher, Philip W. Kantoff, Anuradha Gopalan, Dmitriy Zamarin, David B. Solit, Nikolaus Schultz, Wassim Abida. CDK12 alterations define a distinct molecular subtype of prostate cancers with unique genomic and clinical characteristics [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1308.

Dynamic and consequential consistency of choices between paths of decision trees

The generally prescribed procedure for choosing a decision strategy from a decision tree employs a backward induction analysis that entails 3 fundamental consistency principles: dynamic, consequential, and strategic. The first requires the decision maker to follow through on plans to the end, the second requires the decision maker to focus solely on future events and final consequences given the current state of events, and the third is the conjunction of the first 2. Five experiments were reported to test these principles using different subject populations, different procedures for estimating consistency, and different factors for manipulating the attractiveness of the gamble at the final stage of the tree. The main findings were that strategic and dynamic consistency principles were violated at rates that exceeded choice inconsistency.

Dynamic and consequential consistency of choices between paths of decision trees

The generally prescribed procedure for choosing a decision strategy from a decision tree employs a backward induction analysis that entails 3 fundamental consistency principles: dynamic, consequential, and strategic. The first requires the decision maker to follow through on plans to the end, the second requires the decision maker to focus solely on future events and final consequences given the current state of events, and the third is the conjunction of the first 2. Five experiments were reported to test these principles using different subject populations, different procedures for estimating consistency, and different factors for manipulating the attractiveness of the gamble at the final stage of the tree. The main findings were that strategic and dynamic consistency principles were violated at rates that exceeded choice inconsistency.